1. Field
The present disclosure relates generally to engine systems and, in particular, to open rotor engine systems. Still more particularly, the present disclosure relates to a safety mechanism for handling an undesired blade event in an open rotor engine system.
2. Background
An open rotor engine system is an engine system in which the propeller of the engine system is not contained within the nacelle, or housing, of the engine system. The propeller, which may be also referred to as a fan, is formed by blades connected to a hub. These blades may also be referred to as rotor blades, propeller blades, or fan blades. Rotation of a portion of the hub causes the blades to rotate about an axis through the hub.
With an open rotor engine system, the overall diameter of the propeller may be increased and the overall weight of the engine system reduced. In particular, with an open rotor engine system, the nacelle, seen typically with turbofan engines, may not be needed. Removal of the nacelle may reduce the weight of the engine system and reduce the overall drag induced by the engine system.
Depending on the configuration, an open rotor engine system may have a single propeller or a pair of propellers. The pair of propellers may include a first propeller formed by a first set of blades that rotate in one direction and a second propeller formed by a second set of blades that rotate in the opposite direction.
Prior to usage of an open rotor engine system in an aircraft, the open rotor engine system may need to be certified by one or more regulation agencies, such as, for example, the Federal Aviation Administration (FAA). Certification may require that a safety measure be in place to handle a blade release event. As used herein, a “blade release event” may be a separation of a blade from the hub of the open rotor engine system or a separation of some portion of the blade from the rest of the blade. In particular, certification of the open rotor engine system may require that a safety measure be present to prevent or reduce the possibility of a blade release event having one or more undesired effects on the aircraft and/or on another open rotor engine system of the aircraft.
Additionally, in some cases, certification may require that the aerodynamic influences and/or out-of-balance vibrations caused by a blade release event should have a limited effect on the controllability of the aircraft. Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.